Most dairy manufacturers standardise the fat and some may standardise protein levels of the milk collected to meet consumer expectations for a consistent product all year-round.
One process some manufacturers use to produce a variety of dairy products is ultra-filtration. In this process milk is put through a very fine filter to separate the lactose, minerals and vitamins from the water and protein. The milk-sugar (lactose), vitamins and minerals that filter through are given the term ‘permeate’ and are a valuable part of fresh milk.
Permeate is a technical term which applies to all membrane filtration processes used across food production and other industries. For example, when producing apple juice the fruit is put through a similar filtration process where permeate is the clear juice we end up buying and consuming.
The ultra-filtration process is one way to standardise the protein to a constant value throughout the year. Some other ways include adding or removing fat. Government regulations ensure that milk products conform to food standards for quality, consistency and food safety.
The composition of milk is governed by the Food Standards Australia New Zealand Food Standards Code. These standards are consistent with international standards – milk consumed in nearly all developed countries will have very similar standards. The Code allows manufacturers to add or withdraw milk components to standardise the composition of milk sourced from dairy farms, as required, to produce nutritionally consistent and safe products. Under the Code, the standard for packaged full-fat milk requires that it contain at least 3.2% of fat and 3.0% of protein.
By and large, consumers want to know that every time they purchase fresh milk it will have a consistent composition and taste and standardising milk gives consumers this consistency.